This spreadsheet is a variant of the Eccentrically Loaded Bolt Group (any geometry) Coefficient C Calculator' I previously posted here on Steel Tools.

The spreadsheet has the following input/features:

1.) Any number of bolts can be specified.

2.) Bolt coordinates may be specified, thus allowing formation of bolt group of any geometry or arrangement.

3.) Load eccentricity and rotation can be specified

Spreadsheet Output:

The spreadsheet, as usual, calculates the C coefficient of a bolt group but this time it includes the following:

1.) Location of the INTANTANEOUS CENTER (I.C.) of rotation.

2.) Tabulated calculation of bolt stresses showing how the value of coefficient C is arrived at.

3.) With the I.C. determined, the spreadsheet also shows that the three equations of in-plane static equilibrium (ΣFx=0, ΣFy=0, ΣM=0) for bolt group have been satisfied --- thus, providing the PROOF that the value of coefficient C returned by the spreadsheet is correct.